Researchers found evidence that the invasive barred owl is playing a pivotal role in the continued decline of spotted owls, although habitat loss and climate variation were also important in some parts of the species range. Barred owls compete with spotted owls for space, food and habitat.
This research indicated that since monitoring began spotted owl populations declined 55-77 percent in Washington, 31-68 percent in Oregon and 32-55 percent in California. In addition, population declines are now occurring on study areas in southern Oregon and northern California that were previously experiencing little to no detectable decline through 2009.
Dr. Katie Dugger, a research biologist at the USGS Oregon Cooperative Fish and Wildlife Research Unit, Oregon State University and lead author on the report, said that "This study provides strong evidence that barred owls are negatively affecting spotted owl populations. The presence of barred owls was associated with decreasing spotted owl survival rates in some study areas and spotted owls were disappearing from many of their historical breeding territories as those areas were invaded by barred owls."
The exception was a small area in California where barred owl removals began in 2009, and where long-term population declines were only 9 percent. Spotted owl populations and survival rates have increased on the latter area since the removal of barred owls started. However, further research on barred owl removal is required in other parts of the spotted owl's range—especially in Washington, where barred owl numbers have been high for a long time.
Additionally, said Dugger, "The amount of suitable habitat required by spotted owls for nesting and roosting is important because spotted owl survival, colonization of empty territories, and number of young produced tends to be higher in areas with larger amounts of suitable habitat, at least on some study areas."
Relationships between spotted owl populations and climate was complex and variable, but rangewide, the study results suggested that survival of young spotted owls and their ability to become part of the breeding population increased when winters were drier. This may become a factor in population numbers in the future, given climate change predictions for the Pacific Northwest include warmer, wetter winters.
The collaborative team of 37 researchers analyzed data from 11 study areas that represented 9 percent of the spotted owl range. During the study, field crews monitored how many owls inhabited different territories, and the yearly survival and reproductive success of banded spotted owls. "This type of collaborative research focused on specific management and conservation objectives provides important information for resource managers and policy decision-makers who manage public resources," said Eric Forsman, a coauthor on the study at the USDA Forest Service, Pacific Northwest Research Station.
The paper, "The effects of habitat, climate and barred owls on long-term demography of northern spotted owls," was published in The Condor: Ornithological Applications and authored by Katie M. Dugger, USGS, Oregon Cooperative Fish and Wildlife Research Unit, Oregon State University Department of Fisheries and Wildlife; Eric D. Forsman, USDA Forest Service, Pacific Northwest Research Station; Alan B. Franklin, USDA APHIS National Wildlife Research Center; Raymond Davis, USDA Forest Service, Pacific Northwest Region, and 33 others.
Although they do occur in young forests in some areas, northern spotted owls are strongly associated with old forest in most of their range. The U.S. Fish and Wildlife Service listed the northern spotted owl as threatened in 1990 because of the declines in old-growth forest habitat throughout its range in Washington, Oregon and northern California.
Explore further: US advances plan to kill barred owls in Northwest

The Pacific Northwest forest apparently isn’t big enough for the both of them.
Across that gorgeous emerald range, federally protected northern spotted owls and invasive barred owls are in a nasty turf war. In a new report from the front lines, a U.S. Geological Survey study says that spotted owls that the U.S. Fish and Wildlife Service placed on the endangered species list to save them from logging and development don’t stand a chance.
Research shows that spotted owl populations have fallen by up to 77 percent in Washington state, up to 68 percent in Oregon and by more than half in California, based on some estimates. “In addition, population declines are now occurring on study areas in southern Oregon and northern California that were previously experiencing little to no detectable decline through 2009,” the USGS said in a statement about the report released Wednesday and published in The Condor: Ornithological Applications.
[Why sage grouse could become the next spotted owl]
Barred owls are an eastern species that migrated west. They compete with spotted owls in the mountainous forest for food and space. An earlier Fish and Wildlife study was frank about the severity of the problem. “Barred owls now outnumber spotted owls in many portions of [their] range,” it said. Wherever barred owls were established, spotted owl populations plummeted.
“The U.S. Fish and Wildlife Service is concerned that without barred owl population management, the spotted owl is likely to go extinct in some parts of its range,” Fish and Wildlife said. Wednesday’s USGS study said the only place where spotted owls aren’t gravely affected is a small section of California where barred owls were removed.
Spotted owls had enough problems without this new home invasion. Before they were listed as threatened, timber harvesting and human development converted old growth forest to homes and businesses. The trees the owls prefer were cut for lumber. Forced into corners of the forest, they had less food to hunt and starved, according to Fish and Wildlife.
“Estimates suggest that the amount of suitable habitat available to spotted owls has been reduced by over 60 percent in the last 190 years,” the agency said. Then came the bigger more aggressive barred owl, a gorgeous bird that knows how to adapt to a change in its surroundings. Their diet isn’t as picky as that of spotted owls, so they’re better survivors.
“This study provides strong evidence that barred owls are negatively affecting spotted owl populations,” said Katie Dugger, a research biologist at the USGS Oregon Cooperative Fish and Wildlife Research Unit, Oregon State University and lead author on the report. “The presence of barred owls was associated with decreasing spotted owl survival rates in some study areas, and spotted owls were disappearing from many of their historical breeding territories as those areas were invaded by barred owls.”
[Wildlife groups seek federal protection for Calif. spotted owls, say logging is a threat]
The range of the owls is so large that a team of 37 researchers worked to observe them and analyze the data in 11 study areas. The Oregon State University Department of Fisheries and Wildlife, U.S. Forest Service Pacific Northwest Research Station, USDA APHIS National Wildlife Research Center and the Oregon Cooperative Fish and Wildlife Research Unit were involved.
It doesn’t appear that spotted owls can survive with barred owls in the picture, and certainly not if the barred owls dominate the forest.
“The amount of suitable habitat required by spotted owls for nesting and roosting is important because spotted owl survival, colonization of empty territories, and number of young produced tends to be higher in areas with larger amounts of suitable habitat, at least on some study areas,” Dugger said.
The monarch massacre: nearly a billion butterflies have vanished
Wild animals in the drought-stricken West are dying for a drink
With only 100 left, the world’s smallest porpoise on the verge of extinction

A new study from the Monell Center, the U.S. Department of Agriculture (USDA), and collaborating institutions reports a uniquely identifiable odor signature from mouse models of Alzheimer's disease. The odor signature appears in urine before significant development of Alzheimer-related brain pathology, suggesting that it may be possible to develop a non-invasive tool for early diagnosis of Alzheimer's disease.
"Previous research from the USDA and Monell has focused on body odor changes due to exogenous sources such as viruses or vaccines. Now we have evidence that urinary odor signatures can be altered by changes in the brain characteristic of Alzheimer's disease," said study author Bruce Kimball, Ph.D., a chemical ecologist with the USDA National Wildlife Research Center (NWRC) who is stationed at the Monell Center. "This finding may also have implications for other neurologic diseases."
Identification of an early biomarker for Alzheimer's disease could potentially allow physicians to diagnose the debilitating disorder before the onset of brain decline and mental deterioration, paving the way for upcoming treatments to slow early progression of the disease.
Alzheimer's is the most common form of dementia, afflicting an estimated 5.1 million Americans over the age of 65. There is no test to definitively diagnose Alzheimer's disease in living persons. Although the progression of Alzheimer's currently cannot be stopped or reversed, an accurate diagnosis can give patients and families time to plan for the future and seek treatments for symptom relief.
"While this research is at the proof-of-concept stage, the identification of distinctive odor signatures may someday point the way to human biomarkers to identify Alzheimer's at early stages," said study author Daniel Wesson, Ph.D., a neuroscientist at the Case Western Reserve University School of Medicine.
In the study, published in the online journal Scientific Reports, researchers studied three separate mouse models, known as APP mice, which mimic Alzheimer's-related brain pathology.
Using both behavioral and chemical analyses, the researchers found that each strain of APP mice produced urinary odor profiles that could be distinguished from those of control mice.
The odor changes did not result from the appearance of new chemical compounds, but instead reflected a relative shift of the concentrations of existing urinary compounds.
The odor differences between APP and control mice were mostly independent of age and preceded detectable amounts of plaque build-up in the brains of the APP mice. These findings suggest that the characteristic odor signature is related to the presence of an underlying gene rather than to the actual development of pathological changes in the brain.
Additional studies showed that the distinctive odor profiles could be used to predicatively identify APP mice versus control mice.
Because Alzheimer's is a uniquely human disease, scientists create models of associated brain pathology to study the disease in mice. One of the hallmark pathological indicators of Alzheimer's disease is an excess formation of amyloid plaque deposits in the brain. Scientists mimic this pathology in mouse models by introducing human genes associated with mutations of the amyloid-β precursor protein gene into the mouse genome. These genes are then pharmacologically activated to make excess amyloid-β protein, leading to plaque buildup in the brains of APP mice.
Wesson and study co-author Donald Wilson of the Nathan Kline Institute for Psychiatric Research and New York University School of Medicine utilize the mouse Alzheimer's models to examine the role of olfactory dysfunction as an early biomarker of Alzheimer's disease and other neurodegenerative disorders.
The researchers note that extensive studies are needed to identify and characterize Alzheimer's-related odor signatures in humans.

Wild mallards (Anas platyrhychos) are considered one of the primary reservoir species for avian influenza viruses (AIV). Because AIV circulating in wild birds pose an indirect threat to agriculture and human health, understanding the ecology of AIV and developing risk assessments and surveillance systems for prevention of disease is critical. In this study, mallards were experimentally infected with an H4N6 subtype of AIV by oral inoculation or contact with an H4N6 contaminated water source. Cloacal swabs, oropharyngeal swabs, fecal samples, and water samples were collected daily and tested by real-time RT-PCR (RRT-PCR) for estimation of viral shedding. Fecal samples had significantly higher virus concentrations than oropharyngeal or cloacal swabs and 6 month old ducks shed significantly more viral RNA than 3 month old ducks regardless of sample type. Use of a water source contaminated by AIV infected mallards, was sufficient to transmit virus to naïve mallards, which shed AIV at higher or similar levels as orally-inoculated ducks. Bodies of water could serve as a transmission pathway for AIV in waterfowl. For AIV surveillance purposes, water samples and fecal samples appear to be excellent alternatives or additions to cloacal and oropharyngeal swabbing. Furthermore, duck age (even within hatch-year birds) may be important when interpreting viral shedding results from experimental infections or surveillance. Differential shedding among hatch-year mallards could affect prevalence estimates, modeling of AIV spread, and subsequent risk assessments.

Natural infections by Brucella spp. have been observed in wild populations. Owing to the similarity of lesions and the course of disease across host and pathogen species, the pathogenesis of brucellosis in wildlife is considered similar to that in domestic animals, which has been studied extensively. Similarities include tropism for reproductive and mammary tissues, trophoblast colonisation by the organism, and similar histopathological findings in organs, especially in the reproductive tract. Differences in the disease course exist and are likely to be attributable to immunological and behavioural differences among species. Further study of the pathogenesis and pathobiology of brucellosis in wildlife is expected to yield unique knowledge with application to disease management in both wild and domestic species.

Black bears that eat human foods from trash cans have higher reproductive rates than those living on natural foods, according to a study by Colorado researchers.
The study by researchers with Colorado Parks and Wildlife also found bears that eat human food don't survive as long as those left to the wild.
The bears have been fitted with collars that track their location, helping researchers determine how the animals behave.
The researchers use hair samples to find out how much processed human food the bears had been eating. Scent baits have been set up around the city of Durango to collect hair, the Durango Herald reported (http://tinyurl.com/jl6rrre ).
The study was launched because of increasing conflicts between bears and humans in Colorado, researcher Heather Johnson said.
"There's a lot more risks for a little bear in town," Johnson added.
For example, small cubs can get hit by a car, separated from their mothers or electrocuted while climbing power poles.
The study is being conducted in southwestern Colorado and is scheduled to end next winter.
Wildlife officials say it's difficult to determine what happens to bears in other urban environments.
"It's really tough problem: How many bears are out there, and what kind of impact are we having?" said Stewart Breck, a wildlife ecologist with the National Wildlife Research Center.